There are industrial applications (e.g. press linking, protected areas), in which a manipulator can only travel along a programmed path completely, if a defined travel condition (e.g. press=open) is met. If the travel condition is not met, the manipulator can only travel up to a determined stopping point. At the stopping point, the manipulator must have come to a complete standstill, i.e. be stopped. The manipulator waits in the stopping point for as long as it takes for the travel condition to be met. The stopping of the manipulator is thus the complete braking of all axes of the manipulator. The manipulator has been stopped when the speed of all axes is equal to zero.
A manipulator (robot or industrial robot) is, in accordance with DIN EN ISO 8373, an automatically guided, multi-purpose manipulator equipped with three or more freely-programmable movement axes, which is employed in a fixed or a mobile manner in industrial applications. It can carry grippers or tools (end effectors) or workpieces.
In order for the manipulator to stop at the stopping point, the braking of the manipulator must be commenced at a sufficiently early point on the path, at the so-called braking point, so that the braking point is preferably the point at which the braking must be commenced in order to completely brake the manipulator by the time the stopping point is reached. Braking points are known from the prior art, which are specified points usually taught or programmed into the manipulator by the user. The stopping point is likewise a taught point on the path of the manipulator.
As is known, a conditional stopping of the manipulator by program-controlled modification of the override is possible. Conditional stopping of the manipulator is understood to mean a stopping of the manipulator which takes place only if a respective condition is met. Such a condition can be defined, for example, by means of a travel condition variable, as described below. Override is understood as a chronological scaling variable of the manipulator movement. If the override is 100%, the manipulator travels the programmed movement in the originally programmed time. If the override is, for example, 50%, the manipulator travels the programmed movement in twice the amount of time. If the travel condition is not met when the braking point is reached, a corresponding reduction of the override allows the movement of the manipulator to be slowed and allows the manipulator to be braked. A disadvantage of this process is that the user must find a braking point which is as close as possible to the stopping point and which at the same time allows complete braking of the manipulator by the stopping point location, irrespective of the actual speed. Braking points must thus be selected which lie further away from the stopping point than is necessary for the actual speed of the manipulator, and this results in an extended cycle time.
A conditional stopping by means of blending of the stopping point is also known. Here too, a stopping point and a braking point are taught or programmed by the user. If the manipulator reaches the braking point and the travel condition is not met, the manipulator commences the braking and travels to the stopping point. If, however, the travel condition is met, the stopping point is not entered into, but is instead blended with a defined blending radius. Here too, the braking point must be selected such that the stopping point can be complied with, which leads to extended cycle times. In addition, the path taken in the case of braking deviates from the path without any braking, i.e. the braking is not true to the path. The objective of the present invention is to overcome the disadvantages mentioned. In particular, it is intended to allow a stopping point to be placed or fixed on a given path, without having to teach an additional geometrical path point (preferably braking point).